Telephone-transmitter



H; RICHARDS. TELEPHONE TBA NswMIT TE-R.

(No Model.)

,729 "Patented Jan; 30, 1894.

Np; 51s

UNrrEn STATES PATENT Qrrros.

FRANCIS H. RICHARDS, OF HARTFORD, CONNECTICUT.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 513,729, dated January30, 1894. Application filed December 4, 1893- Serial No. 492,698 (Nomodel.)

To all whom itmay concern:

Be it known that I, FRANCIS H. RICHARDS, a citizen of the United States,residing at Hartford, in the county of Hartford and State ofConnecticut, have invented certain new and useful Improvements 'inTelephonic Transmitters, of which the following is a specification.

This invention relates to transmitters for electric speaking telephones;the object being to furnish an improved instrument of this class inwhich the required undulatory currents may be produced by variation ofthe current-strength resulting from a variation in the amount of contactbetween surfacecontacting electrodes.

In the drawings accompanying and forming a part of this specification,Figure 1 is a sectional plan view 'oftelephone transmitter madeaccording tomy present improvements. Fig. 2 is a front sectionalelevation of the same, on line a'-a, Fig. 1. Fig. 3 is a transversesectional view, on line b-b, Fig. 1. Fig. 4 is a diagrammatic viewillustrative of one of the features or details of the invention. Fig. 5is a front elevation of the principal member of the electrode-carrier.Fig. 6 is an edge view of the same, as seen from the righthand in Fig.2, and corresponding to the position of the same in Fig. Fig. 7 is aside view of the spring-arm of' the electrode-carrier. Fig. 8 is anedge'view of the same with the operativeelectrode fixed thereon.

Similar characters designate like parts in all the figures. My improvedtelephone transmitter has a framework or casing, a plate sensitive tosound-waves, a compound electrode supported by the framework, and afollower-electrode operatively connected with the sensitive plate andsupported fora working-movement against the working-face of the compoundelectrode. The operative electrode is shown mounted upon a carrier orlever which is supported for movement laterally of itself in the planeof the working-faces of the electrodes; so that the said movement,though it be of considerable extent and the carrier-lever be relativelyshort, will not tend to vary the position of either electroderelatively'to' the plane of their working-faces, but will only operateto slide the one electrode upon the other in true coincidence with thatplane.

The casing or frame, F, may be of any convenient description,beingpreferably of the usual box-like form and consisting of the foursides, 2, 3, 4 and 5, the front-plate, 6, and the top-plate, 7, allsuitably held together. The

diaphragm, or sensitive-plate, 8, is fixed in place just within thefront-plate,atter the ordinary manner of supporting the sensitiveplatesof this class of instruments; and a mouth-piece, 9, is or maybe providedaround the aperture, 10, of the front-plate, for directing thesound-waves against the sensitiveplate. This plate and some suitableconnection therewith constitute the means for actuating themechanically-operative electrode, as hereinafter more fully set forth.

The compound electrode, which is designated in a general way by B,consists of two parts, the conducting or electrical member 11 and thenon-conducting ornon-electrical member 12; these parts or members areheld in rigid relation the one to the other, and together constituteacompound electrode whose Working-face e consists of two fields or areas,11' and 12', the one electrical and the other non-electrical. Theelectrode Bis shown supported on a pivot or like device, 17, between thewings, 17 and 177, of a bracket, 20, which is suitably fixed; (as, forinstance, by the screw 21) to the framework of the instrument. Whensaid, bracket 20 is of metal (as it is supposed to be in the presentcase) one I of the terminals, 30,-of the usual electric circuit may beconnected with the compound electrode through the usual clamp-device,31.

The two parts-1 1 and 12 of the compound electrode are made rigidlyadherent the one to the other, by means of a thin layer of cement or aweld-surface equivalent thereto, in the line f, Fig. 4, so that saidcompound electrode constitutes a single unitary element of thetransmitter, and so that the two portions 11' and 1 2 of theworking-face e of said electrode are held in permanent coincidenceindependently of the device or devices for sup porting this electrode inthe instrument. In practice the non-electrical portion of the compoundelectrode may be formed of any substance of relatively lowconductity andalso adapted to have made thereon a smooth and true working-face; andthe electrical portion may be formed of any substance of relativelygreater electrical conductivity, and adapted to have made thereon thedescribed workingface.

The operative electrode, 19, is carried upon one end of a lever, 13,which is shown supported at the opposite end thereof upon pivots, 13'and 13", in a bracket, 14, suitably fixed to the framework of theinstrument. To this lever, or electrode-carrier, the other terminal, 32,of the electric circuit is shown connected at 33 by means of abinding-screw, after a well-known manner. The pivots l3 and 13",in thepreferred form thereof herein shown, consist of screws adjustablelongitudinally thereof in the bracket for the purpose of properlyregulating the pivotal connection with the lever, and also for adjustingthe lever in the line of its axis to carry the same and the operativeelectrode 19 toward or from the compound electrode, as may be required.The axis of the pivotal connection or joint here described is arrangedvertical to the plane (extended) of the working-faces of the electrodes,so that the vibrational movement of the lever, and of the operativeelectrode carried thereby, is truly coincident with said plane.

According to one feature of my present invention, the co-acting edges ofthe electrical fields (one of these fields being the surface 11' of thecompound electrode, and the other field being the working-face of theoperative electrode 19) are made divergent, for the purpose of modifyingthe ratios of the overlapping electrical surfaces in the successivepositions, respectively, of the operative electrode. This will beunderstood by means of the diagrammatic view, Fig. 4, in which the edge,19',of the operative electrode 19 is shown formed upon a curved ordivergent line crossing the line fof the compound electrode (when thisis in the position there shown) at an angle thereto; which angle varies,as will be evident from the drawings, with the movement of the operativeelectrode. The projecting portion or point 19 of the operative electrodeis intended to always extend onto the electrical field ll of thecompound electrode, so as to prevent the sliding action of one electrodeupon the other (within the normal working limits of such movement) fromentirely interrupting the electrical circuit. At the same time, bymodifying the curvature or inclination of said edge-lines f and 19, ofthe two electrodes respectively, the ratio of variation oftheoverlapping electrical surfaces may be materially modified, within agiven limit of movement of the one electrode relatively to the other. Inthis connection, it should be observed that this feature of my presentinvention is also applicable to the arrangement of electrodes set forthin my aforesaid prior application; also a curved or inclinedelectrical-field edge may be made on the compound electrode; in thiscase, the line 1 of said electrode will, of course, be inclined orcurved, instead of being formed straight and located as herein shown.

The mechanically-operative electrode, according to one feature of mypresent invention, is carried upon the upper end of aspringarm, 25,which is rigidly supported by one end thereof in the main lever 13between the opposite arms, 26 and 26, of this lever. Said arms are shownslightly diverging on curved lines from said spring-lever, so as toprovide for a slight movement of the spring-lever and the electrodecarried thereby, relatively to the upper end of the main lever 13. Thisis for the purpose of slightly modifying the normal action of theoperative electrode, and thereby securing a smoother and more regularoperation of the same relatively to the harsher vibrations of thediaphragm; but it should be noted that the carrier 25 may be integral,and made substantially non-elastic, without departing from the principalfeatures of my present invention.

For clearness of illustration, the several working-details of theapparatus herein described are shown somewhat enlarged relatively to thesize of the instrument as a whole; but it will be understood that themagnitude of the electrodes relatively to the sensitiveplate and to thegeneral proportions of the instrument, depends, in practice, very muchupon the electrical conductivity of the substances of which theelectrical portions of the electrodes are formed. It is deemedpreferable to make said portions of relatively low conducting power soas to require a considerable amount of overlapping electrical surfacefor conveying the required amount of current, and so that thevibrational action of the operative electrode need not be restrictedwithin very narrow limits.

It will be understood that by electrical field and non-electrical fieldis meant portions of the working-face of the compound electrodeofdifferent degrees of electrical conductivity; so that on the movement ofthe opposite electrode over the line between said fields, the electricalcurrent, when the electrodes are in circuit, will be increased ordiminished accordingly as said opposite electrode is moved in onedirection or the other. The relatively non-electrical field of thecompound electrode is shown of larger area than the electrical field ofthe opposite electrode, so that neither the total area ofsurface-contact, nor the area of surface pressure, will be varied by thesliding of one electrode upon the other, even if this action be so greatas to carry the electrical field of one electrode en tirely off fromtheelectrical field 0f the opposite electrode.

In some cases thecompound electrode when carried upon the framework asherein shown, may be adjusted toward and from the operative non-compoundelectrode; the described means for adjusting the latter electrode beingthen omitted.

Having thus described my invention, I claim- 1. In a telephonictransmitter of the class specified, the combination with a platesensitive to sound-waves, ofa pair of electrodes in circuit and one ofthem having-a compound working-face comprising an electrical andnon-electrical field, and the other electrode bearing against saidworking-face and extending onto both of said fields, and anelectrodecarrier separate from but in operative connection with theplate and supporting one of the electrodes, and itself supported forvibrational movementonly in a plane in coincidence with the plane ofsaid working-face, substantially as described and for the purposespecified. 1

2. In a telephonic transmitter of the class specified, the combinationwith a plate sensitive to sound-Waves, of an electrode fixed to theframework of the transmitter and having a compound working-facecomprising an electrical and non electrical fields, said workingfacebeing located vertical-to saidplate, an operative electrode bearing uponsaid compound working-face, and an electrode-carrier carrying theoperative electrode and in operative connection with the sensitive plateand supported for swinging movement in the plane of said working-faceupon an axis in substantial parallelism with said plate, substantiallyas described.

3. In a telephonic-transmitter, the combination with the fixedelectrode, and with an operative electrode fitted to slide thereon, ofan electrode-carrier supported for lateral movement and comprising aprincipal member and a spring-arm supported thereon and carrying theoperative electrode, and means for impartingvibrational movement to thecarrier from sound-waves, whereby the normal action of the operativeelectrode is modified, substantially as described.

4. In a telephonic transmitter, the combination with a sensitive plateandthe fixedly-located compound electrode, of the lever and theelectrode carried thereby for operative movement only in the plane ofits workingface, and means for adjusting the lever on its axial linetoward and from the fixed electrode in a direction vertical to theWorking faces thereof, substantially as described and for the purposespecified. I

5. In a telephonic transmitter of the class specified, the combinationwith a compound electrode having its working-face composed of adjacentelectrical and non-electrical fields, of an electrode supported forsliding movement on said working-face and having the edge thereof set ona line divergent from the edge of the electrical field of the compoundelectrode, substantially as described.

6. In a telephonic transmitter of the class specified, the combinationwith a compound electrode having its working-face composed of adjacentelectrical and non-electricalfields, of an electrode supported forsliding movement on said working-face and having the edge thereof set ona curved line divergent from the edge of the electrical field of thecompound electrode, substantially as described.

7. The herein-described compound electrode for telephonic transmitters,which consists in a relatively-electrical body or mem ber combined witha relatively non-electrical body or member set on one side of and made*rigidly adherent to the other, said members having working surfaces incoincident planes and constitutlng a compound working-face,

substantially as described.

8. In a telephonic instrument, the combination with a plate sensitive tosound waves, of an electrode fixed to the framework of theinstrument'and having a compound workingface comprising electrical andnon-electrical fields, said working-face being located vertically tosaid plate, an operative non-compound electrode bearing on said compoundworking-face, and an electrode-carrier carrying the operative electrodeand in operative connection with the sensitive plate and supported formovement in the plane of said working-face, substantially as described.

9. In a telephonic instrument, thecombination with the sensitive plateof the two electrodes, one compound and non-operative and carried on theframework of the instrument, and the other carried bya lever foroperative movement only in the plane of its workingface, and means foradjusting one of the electrodes toward and from the other in a directionvertical to the working-faces thereof, substantially as described.

10. In a telephonic instrument, the combination of two electrodesadapted and in position for sliding contact the one upon the other, andone of them having a compound working-face comprising relativelyelectrical and non-electrical fields, and means for operating oneelectrode relatively to the other, substantially as described.

11. In a telephonic instrument, the combination with one electrodehaving its workingface an electrical field, another electrode sliding onthe first electrode and having its working-face formed in part of anelectrical field and in part of a non-electrical field of larger areathan the electrical field of the first electrode, substantially asdescribed.

12. In a telephonic instrument, the combination with one electrodehaving its working face an electrical field, of another electrode havingits working-face of larger area than and bearing on the face of saidfirst electrode, and divided into relatively electrical andnonelectrical fields each extending in part over the working-face ofsaid first electrode, one electrode being supported for sliding movementupon the face of the opposite electrode, substantially as described.

13. In a telephonic transmitter, the combination with a plate sensitiveto sound-waves, of a pair of electrodes in circuit, and one of themhaving a compound working-face com prising an electrical andanon-electrical field, and the other electrode bearing against saidworking-face and extending onto both of said fields, and meansoperatively connecting one of the electrodes with the plate and adaptedto move the operative electrode in the plane of its working-face,substantially as described.

14. In a telephonic transmitter, the combination with a plate sensitiveto sound-waves and with a pair of electrodes in circuit, and

one of them havinga compound working-face I5 of the electrodes, inposition for vibratory 2o movement in the plane of its electrical face,and operatively connected with the sensitive plate, substantially asdescribed.

FRANCIS H. RICHARDS.

Witnesses:

FRED. J. DOLE, N. E. O. WHITNEY.

